Inflammatory bowel disease (IBD) is a general name for diseases of unknown causes that are represented by ulcerative colitis and Crohn's disease which cause chronic inflammation and/or ulceration of the mucosa of the large and small intestines. The majority of the patients are affected at relatively young ages, i.e., in their teens or twenties, and they develop clinical symptoms such as diarrhea, fever, and abdominal pain and systemic inflammatory symptoms. There have been problems that the patients become unable to efficiently absorb nutrients of foods and drinks taken orally, and their social life is seriously affected by food restriction and increased stool frequency. As to the possible causes of IBDs, theories that have been reported include autoimmune abnormality and enterobacteria, which still remain unclear, no treatment method leading to complete cure has been found up until today (Non-patent Document 1).
As a therapeutic agent for IBDs such as ulcerative colitis, salazosulfapyridine, 5-aminosalicylic acid, steroids, immunosuppressive agents, and the like are commonly used. However, sufficient treatment effect cannot be obtained by these therapeutic agents, and side effects caused by long term administration of steroids and immunosuppressive agents become a serious problem (Non-patent Document 1).
Recently, it has been shown that Propionibacterium freudenreichii, one of propionic acid bacteria, produces bifidogenic growth stimulators (BGSs) and that the active component thereof is 1,4-dihydroxy-2-naphthoic acid (DHNA). DHNA is known to have effects of promoting the growth of bifidobacteria and improving inflammatory conditions of the mucosa in IBDs as well as suppressing infiltration of activated immune cells (for example, refer to Patent Document 1). Further, DHNA has been reported to alleviate abdominal discomfort associated with milk intake in milk intolerance and to be useful for prevention and/or therapy of metabolic bone diseases (refer to the same reference). Since this DHNA is produced by propionic acid bacteria in large amounts both intracellularly and extracellualy, a fermentation method using a propionic acid bacterium is attracting attention as a highly safe production method of DHNA. A fermentation product of a propionic acid bacterium obtained by a fermentation technique contains DHNA at a high concentration and is approved as a food for specified health use that regulates the functions of the intestines.    [Patent Document 1] WO publication 03/016544 pamphlet    [Non-patent Document 1] Shoukakibyou seminar 77 Enshousei Chousikkan-Atarashii shiten (in Japanese) (Seminar on Gastrointestinal Diseases 77 Inflammatory Bowel Disease—A New View) Tadao Baba, Ed., Herusu Shuppan, Co., Inc. 1999